If I remember correctly:
The lid helps because you no longer have those silencer growths hanging off the airpath and causing turbulence. So one lid is going to work much the same as another.
The free Ram Air mod is good for the non-WS6 models because of the smaller opening at the front of the airbox, and lack of hood intake. The WS6 models have a much larger front opening, plus the hood intakes, so it isn't as big of a deal. You will heat-soak when stationary as warm air from your radiator will rise into the intake. But the moment you get moving, you'll ingest cool air again.
The LS1 loves to breathe, so I felt that anything to help that is a good thing. So I'd probably do both. But also remember that this is 10 year old expereince talking. Any updates/improvements in the last decade I'm not familiar with. For example, removing the flow straightener infront of the MAF was considered a good mod at one point. Now I know how wrong that is.